ASTM_G_167_-_15.pdf

Designation:G16715Standard Test Method forCalibration of a Pyranometer Using a Pyrheliometer1This standard is issued under the fixed designation G167;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONAccurate and precise measurements of total global(hemispherical)solar irradiance are required inthe assessment of irradiance and radiant exposure in the testing of exposed materials,determinationof the energy available to solar collection devices,and assessment of global and hemispherical solarradiation for meteorological purposes.This test method requires calibrations traceable to the World Radiometric Reference(WRR),whichrepresents the SI units of irradiance.The WRR is determined by a group of selected absolutepyrheliometers maintained by the World Meteorological Organization(WMO)in Davos,Switzerland.Realization of the WRR in the United States,and other countries,is accomplished by theintercomparison of absolute pyrheliometers with the World Radiometric Group(WRG)through aseries of intercomparisons that include the International Pyrheliometric Conferences held every fiveyears in Davos.The intercomparison of absolute pyrheliometers is covered by procedures adopted byWMO and is not covered by this test method.It should be emphasized that“calibration of a pyranometer”essentially means the transfer of theWRR scale from a pyrheliometer to a pyranometer under specific experimental procedures.1.Scope1.1 This test method covers an integration of previous TestMethod E913 dealing with the calibration of pyranometerswith axis vertical and previous Test Method E941 on calibra-tion of pyranometers with axis tilted.This amalgamation of thetwo methods essentially harmonizes the methodology with ISO9846.1.2 This test method is applicable to all pyranometersregardless of the radiation receptor employed,and is applicableto pyranometers in horizontal as well as tilted positions.1.3 This test method is mandatory for the calibration of allsecondary standard pyranometers as defined by the WorldMeteorological Organization(WMO)and ISO 9060,and forany pyranometer used as a reference pyranometer in thetransfer of calibration using Test Method E842.1.4 Two types of calibrations are covered:Type I calibra-tions employ a self-calibrating,absolute pyrheliometer,andType II calibrations employ a secondary reference pyrheliom-eter as the reference standard(secondary reference pyrheliom-eters are defined by WMO and ISO 9060).1.5 Calibrations of reference pyranometers may be per-formed by a method that makes use of either an altazimuth orequatorial tracking mount in which the axis of the radiometersradiation receptor is aligned with the sun during the shadingdisk test.1.6 The determination of the dependence of the calibrationfactor(calibration function)on variable parameters is calledcharacterization.The characterization of pyranometers is notspecifically covered by this method.1.7 This test method is applicable only to calibration pro-cedures using the sun as the light source.1.8 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E772 Terminology of Solar Energy ConversionE824 Test Method for Transfer of Calibration From Refer-ence to Field Radiometers1This test method is under the jurisdiction of ASTM Committee G03 onWeathering and Durability and is the direct responsibility of Subcommittee G03.09on Radiometry.Current edition approved Feb.1,2015.Published March 2015.Originallyapproved in 2000.Last previous edition approved in 2010 as G167 05(2010).DOI:10.1520/G0167-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.2 WMO Document:3World Meteorological Organization(WMO),“Measurementof Radiation”Guide to Meteorological Instruments andMethods of Observation,seventh ed.,WMO-No.8,Ge-neva2.3 ISO Standards:4ISO 9060:1990 Solar EnergySpecification and Classifica-tion of Instruments for Measuring Hemispherical Solarand Direct Solar RadiationISO 9846:1993 Solar EnergyCalibration of a PyranometerUsing a Pyrheliometer3.Terminology3.1 Definitions:3.1.1 See Terminology E772.3.2 Definitions of Terms Specific to This Standard:3.2.1 altazimuth mount,na tracking mount capable ofrotation about orthogonal altitude and azimuth axes;trackingmay be manual or